MICROSTRUCTURAL CHARACTERIZATION OF AlSi7Mg/AlN AND AlSi12Mg/SiC COMPOSITES OBTAINED BY REACTIVE GAS INJECTION METHOD

Abstract

The paper studies the microstructural and chemical characterization of in-situ AlSi7Mg/AlN and AlSi12Mg/SiC composites obtained by the injection of reactive gases in aluminum alloy melt. The samples were characterized using optical microscopy, X-ray diffraction and SEM. The chemical composition was determined by inductive coupled plasma spectrometry. Samples taken from different parts of the product revealed uneven compositional distribution of reinforcements and primary silicon in the alloy matrix. In the upper side of the products was found a significant enrichment of the reinforcing particles, for both composite systems, caused by the small dimensions of the particles and the upward movement of the injected gas, during the bubbling process. Optical micrographs revealed SiC and AlN particles of irregular shapes and small sizes (<10µm).